Project Summary Ovarian carcinoma is the fifth deadliest cancer among women in the United States. In spite of advances in surgical resection and platinum-taxane combination therapy over the past several decades, cure rates remain relatively low (~30%) and a majority of women diagnosed with advanced ovarian cancer will die with drug-resistant disease within 5 years. The long-term goal of this project, ?RNA-Binding Proteins as Molecular Integrators that Control the Response of HGSOC to Anti-Cancer Therapies?, is to identify specific RNA-binding proteins that, together with their upstream protein kinase regulators, control the resistance and sensitivity of high-grade serous ovarian cancers to these clinically used first line anti-cancer therapies. The project involves: (1) a detailed computational analysis that queries pre-existing publically available RNA expression data using RNA-BP recognition motifs to identify specific RNA binding proteins whose mRNA targets are up- or down- regulated in ovarian cancer patients with chemo-sensitive versus chemo-resistant tumors; and (2) an independent CRISPR-interference and CRISPR-activation genome-wide screen for RNA-BPs whose manipulation alters the resistance and sensitivity of ovarian cancer cells to platinum and taxane agents in vitro, and in vivo using cell line xenografts and human PDX ovarian cancer mouse models. The RNA-BPs identify by these two complimentary approaches, together with a collection of RNA-BPs that we have already identified in previous experiments and preliminary data, are then directly validated for their effects on drug resistance in these model systems, and the identity of their bound RNAs and their effects on gene expression determined using CLIP technologies and RNA-Seq. In selected cases the importance of specific phosphorylation sites on RNA-BP function is examined to further elucidate the molecular basis for anti-cancer drug resistance through pathway-specific regulation of RNA-BP action. The project builds on a broad foundation of expertise and related work from all of the co-Investigators laboratories. Expected outcomes from the studies include the identification of specific RNA-BPs and upstream regulatory kinase pathways whose targeting can prevent or reverse the resistance of ovarian cancers to current clinically used front-lime therapeutics; the elucidation of new molecular circuits that control gene expression in cancers after chemotherapy treatment; and the creation of a suite of web-based tools available to the entire scientific community that can be used to query any set of differentially expressed genes for RNA-BP-based regulation, particularly in a form that is optimized for analysis of new and existing cancer patient RNA expression datasets.